Josep Álvarez

Epidemiology of pertussis in a country with high vaccination coverage

INTRODUCTION Pertussis has been a preventable disease in Catalonia since 1965, but the annual number of cases remains high. The aim of this study was to analyze the epidemiology of pertussis in Catalonia and its implications for control purposes. METHODS An epidemiological study was carried out in Catalonia between 2004 and 2008. Pertussis cases reported to the Department of Health were collected and disease reports were filled out with the case information. Incidence rates, rate ratios (RR) and their 95% confidence intervals (CI) were calculated. RESULTS 963 cases were reported: 555 (57.6%) were confirmed and 408 (42.4%) were suspected cases. The reported incidence rate was 2.01 × 10(-5) person years in 2004 and 4.34 in 2008. The biggest increase in cases between 2004 and 2008 was observed in the ≥35 years age group (RR: 6.98; 95%CI: 2.11-36.36). 303 (31.5%) patients were hospitalized, of whom 93.7% were aged <1 year. Clinical differences were observed in paroxysmal cough (83.8% in suspected and 76.4% in confirmed cases, p=0.005), posttussive vomiting (47.1% and 36.1%, respectively, p=0.001), apnoea (13.7% and 21.3%, respectively, p=0.003) and fever (20.1% and 12.4%, respectively, p=0.001). CONCLUSION Pertussis incidence rates increased during the study period, with the greatest increase occurring in the ≥35 years age group. A booster dose of vaccine in young people could reduce the circulation of B. pertussis in adolescents and adults and indirectly reduce the incidence in children.

Epidemiology of foodborne norovirus outbreaks in Catalonia, Spain.

BackgroundNoroviruses are one of the principal biological agents associated with the consumption of contaminated food. The objective of this study was to analyse the size and epidemiological characteristics of foodborne outbreaks of gastroenteritis in Catalonia, a region in the northeast of Spain.MethodsIn all reported outbreaks of gastroenteritis associated with food consumption, faecal samples of persons affected were analysed for bacteria and viruses and selectively for parasites. Study variables included the setting, the number of people exposed, age, sex, clinical signs and hospital admissions. The study was carried out from October 2004 to October 2005.ResultsOf the 181 outbreaks reported during the study period, 72 were caused by Salmonella and 30 by norovirus (NoV); the incidence rates were 14.5 and 9.9 per 100,000 person-years, respectively. In 50% of the NoV outbreaks and 27% of the bacterial outbreaks (p = 0.03) the number of persons affected was ≥10; 66.7% of NoV outbreaks occurred in restaurants; no differences in the attack rates were observed according to the etiology. Hospitalizations were more common (p = 0.03) in bacterial outbreaks (8.6%) than in NoV outbreaks (0.15%). Secondary cases accounted for 4% of cases in NoV outbreaks compared with 0.3% of cases in bacterial outbreaks (p < 0.001)ConclusionNorovirus outbreaks were larger but less frequent than bacterial outbreaks, suggesting that underreporting is greater for NoV outbreaks. Food handlers should receive training on the transmission of infections in diverse situations. Very strict control measures on handwashing and environmental disinfection should be adopted in closed or partially-closed institutions.

Impact of the Legionella urinary antigen test on epidemiological trends in community outbreaks of legionellosis in Catalonia, Spain, 1990–2004

OBJECTIVES To describe the characteristics of community outbreaks of legionellosis in Catalonia, Spain from 1990 to 2004, to compare two time periods (1990-1996 and 1997-2004), and to assess the influence of outbreak characteristics on the case fatality rate (CFR). METHODS This is a descriptive analysis of the outbreaks detected by epidemiological surveillance units in Catalonia. Variables potentially related to the CFR were analyzed by logistic regression. RESULTS Of the 118 outbreaks involving 690 patients (overall CFR 4.5%), the urinary antigen test (UAT) was used for first case diagnosis in 80.5%. The origin of the outbreak was identified as a cooling tower in 35.6%, as a water distribution system in a public building in 14.4%, and a water distribution system at other sites in 7.6%. Statistically significant differences were found in the CFR (12.2% vs. 3.9%; p=0.018) and detection of the first case by UAT (0.0% vs. 87.2%; p<0.001) between the two time periods investigated. Logistic regression showed an increase in the CFR according to outbreak size (adjusted odds ratio (aOR) 1.18; 95% confidence interval (CI) 1.05-1.33) that was significantly lower in the second period (aOR 0.09; 95% CI 0.04-0.20). CONCLUSIONS Since the UAT was introduced, early diagnosis and treatment has helped to improve the outcomes and CFR of cases involved in outbreaks of legionellosis.

Smoking in tuberculosis patients increases the risk of infection in their contacts

OBJECTIVE To determine the risk of latent tuberculous infection (LTBI) among contacts of smokers with tuberculosis (TB). METHODS A study was conducted to determine the prevalence of LTBI among contacts of TB cases aged >14 years in Catalonia, Spain. A survey was carried out for each TB case and their contacts. LTBI was diagnosed using the tuberculin skin test (≥5 mm). The risk of LTBI associated with smoking was determined by multi-variate logistic regression analysis, with adjusted odds ratio (aOR) and their 95% confidence intervals (CI). RESULTS The smoking prevalence among TB cases was 40.7% (439/1079). The prevalence of LTBI among their contacts was 29.7% (2281/7673). It was higher among contacts of smoking index cases (35.3%) than among those of non-smokers (25.7%). Smoking was independently associated with an increased risk of LTBI among contacts (aOR 1.5, 95%CI 1.3-1.7), and was estimated to be responsible for 12.8% of infections. CONCLUSIONS Index case smoking increases the risk of LTBI and should be systematically investigated. A reduction in smoking could lower the risk of infection substantially.

Estudio descriptivo de los brotes de hepatitis A investigados en Cataluña (1999-2003)

Antecedentes y objetivo Actualmente Espana presenta un patron de baja endemicidad de hepatitis A que favorece que la enfermedad se manifieste en forma de brotes en colectivos susceptibles. El objetivo de este estudio es analizar los brotes de hepatitis A investigados en Cataluna durante el periodo 1999-2003. Metodos Se definieron criterios para la inclusion de los brotes y posteriormente se clasificaron segun el mecanismo de transmision. Se analizaron variables de espacio, tiempo, sociodemograficas, ambito, factores de riesgo y medidas preventivas. Se calcularon las tasas de incidencia y la razon de tasas segun edad y sexo. Resultados De 74 brotes, 73 cumplieron los criterios de inclusion: la mayoria con transmision persona-persona (83,8%) y el resto con fuente de infeccion comun (14,9%). En total, se incluyeron 334 casos (incidencia acumulada 1999-2003:5,27 por 100.000 habitantes), con una mediana de edad de 24,5 anos. Los ambitos con mas casos fueron el familiar (143), el comunitario (97) y el escolar/guarderia (87). El numero de casos por brote oscilo entre 2 y 11, excepto un brote que afecto a 83 varones con practicas homosexuales de riesgo. Pertenecer a los grupos de edad de baja inmunidad (ninos y adultos jovenes) y viajar o proceder de zonas endemicas fueron las caracteristicas mas importantes relacionadas con el caso indice y/o con los casos coprimarios. Conclusion Los brotes de hepatitis A en Cataluna todavia son frecuentes. La mayoria se producen en el ambito familiar, por transmision persona-persona, y en los subgrupos de poblacion mas susceptibles a la infeccion (trabajadores de guarderias o escuelas, viajeros y varones con practicas homosexuales de riesgo).

Characteristics of Cases Hospitalized for Severe Pandemic (H1N1) 2009 in Catalonia

Fundamentos. Las pandemias de gripe pueden comportar una mayor gravedad. El objetivo fue determinar las caracteristicas de los casos graves hospitalizados de gripe pandemica en Cataluna y estudiar factores de riesgo de ingreso en UCI. Metodos: Se realizo un estudio epidemiologico observacional y prospectivo de los casos nuevos de gripe pandemica hospitalizados por su gravedad en el periodo: junio del 2009 hasta mayo del 2010. Se solicito a los centros sanitarios la declaracion de los casos que cumplieron la definicion de caso grave y en los que se confirmo la presencia del virus pandemico. Mediante una encuesta epidemiologica se recogio informacion sobre variables demograficas, clinica, factores de riesgo, tratamiento y evolucion clinica. Las diferencias entre los casos en UCI respecto al resto de casos graves se estudiaron con la odds ratio ajustada (ORa) mediante un modelo de regresion logistica no condicional. Resultados: Se detectaron 773 casos graves de gripe pandemica; 465 (60,2%) presentaron al menos un factor de riesgo y los mas prevalentes fueron: embarazo 19 (13%), asma 87 (12%); enfermedad pulmonar obstructiva cronica 87 (11,4%) y cardiopatias 80 (10,5%). Precisaron ingreso en una unidad de cuidados intensivos 293 pacientes (37,9%). Los factores asociados al ingreso en UCI fueron la obesidad IMC>40 (ORa=2,5; IC 95% 1,4-4,5) y la enfermedad hepatica cronica (ORa=2,3; IC 95% 1,1-4,8). Conclusiones: Se confirma la alta prevalencia de embarazo, enfermedades respiratorias cronicas, diabetes y obesidad entre los casos graves. La obesidad morbida se comporta como un factor de riesgo de ingreso en UCI y por ello debe ser un indicador de vacunacion antigripal.

Declaración de los nuevos diagnósticos de infección por el VIH en Cataluña. Implementación y resultados

Objetivos: Describir los resultados de la notificacion de nuevos diagnosticos de infeccion por el virus de la inmunodeficiencia humana (NDIVIH) en Cataluna (2001-2003), y comparar las caracteristicas de la epidemia como resultado de la utilizacion de este nuevo sistema de informacion junto con el Registro de casos de sida de Cataluna, con las halladas unicamente en el Registro de casos de sida. Metodos: Datos de las notificaciones de NDIVIH y de casos de sida entre 2001 y 2003 en Cataluna. Resultados: Entre los NDIVIH (n = 1.765), la via de transmision mas frecuente fue las relaciones heterosexuales (46,8%), seguida de las relaciones homosexuales entre varones (26,7%) y el uso de drogas por via parenteral (19,9%). Entre los 1.210 casos de sida, la forma de transmision mas frecuente fue el uso de drogas por via parenteral (42,2%), seguida de relaciones heterosexuales (34,5%) y de las relaciones homosexuales entre varones (18,0%). La diferencia de utilizar una o 2 fuentes de informacion respecto a la variable via de transmision de la infeccion fue estadisticamente significativa. Conclusiones: El sistema de informacion basado en los datos sobre NDIVIH es viable, ha sido util para conseguir los objetivos previstos en el sistema de vigilancia epidemiologica del VIH y proporciona informacion mas precisa que el Registro de sida para describir los actuales patrones de transmision del virus. La exhaustividad del nuevo sistema de informacion podria mejorar mediante la incorporacion del diagnostico de infeccion al sistema de enfermedades de declaracion obligatoria.

BROTES POR NOROVIRUS EN RESIDENCIAS Y CENTROS SANITARIOS DE CATALUÑA

BACKGROUND The low infectious dose and multiple transmission routes favour the appearance of norovirus outbreaks. The objective of this study was to compare the incidence of norovirus outbreaks in hospitals and nursing homes in Catalonia. METHODS A descriptive study of norovirus outbreaks between 15/10/2004 and 30/10/2005 was carried out. An epidemiological survey was completed for each outbreak. Norovirus in clinical samples was determined by PCR techniques. The incidence in each centre and the annual incidence of outbreaks by centre were calculated. Differences were calculated using the chi-square test and the Students t test, taking a p value of > 0.05 as significant. RESULTS Seventeen outbreaks (6 in hospitals and 11 in nursing homes) were detected. The global attack rate was 33.4% (652/1951) and was slightly higher in nursing homes (35.2%) than in hospitals (31.4%). A total of 94.1% (16/17) of outbreaks were caused by person-to-person transmission and only 5.9% (1/17) by foods. The mean number of days between the first and last case was 11.4 (SD = 6.9). The mean duration of symptoms was 2.39 days (SD=1.6), and was higher hospitals, 2.63 (SD=1.7), than in nursing homes, 1.97 (SD=1.7) (p < 0.0001). CONCLUSIONS Norovirus is responsible for a large number of outbreaks due to person-to-person transmission. Control should be standardized to reduce the number and duration of outbreaks.

Pandemic A/H1N1 influenza: Transmission of the first cases in Spain

INTRODUCTION Pandemic A/H1N1 influenza emerged in Mexico at the end of March 2009. Since then, it is still important to provide evidences that contributed to the international spread of the virus and to ascertain the attack rate of this new strain of influenza among the first cases in Spain that led to identify the first transmission in Europe. METHODS Three pandemic A/H1N1 influenza groups related to an overseas flight were studied: 71 student group, 94 remaining passengers, and 68 contacts of confirmed cases. The attack rate with their 95% confidence interval (CI) among the student group and contacts was calculated. On April 26th, when the first cases were notified, strong preventive measures were implemented among the student group and the contacts of the confirmed cases. RESULTS On 27th April, the first pandemic A/H1N1 influenza cases confirmed in Spain were three students that came back from Mexico by airplane. A student generated the first native case in Spain and one of the first cases in Europe. Similar attack rates were found between the student group (14.1%; CI: 12.1-16.1) and their contacts (13.2%; CI: 4.4-22.0), but no cases among remaining passengers were detected, suggesting low transmission risk during air travel. CONCLUSION The first cases of pandemic A/H1N1 influenza in Spain were imported by airplane from Mexico. Preventive efforts to reduce the impact of the influenza influenced that primary and secondary rates were lower than first estimations by WHO.

Mumps: a year of enhanced surveillance in Catalonia, Spain.

Mumps is a vaccine-preventable disease candidate for elimination. Positive predictive value (PPV) of clinical case definition was assessed. During 2007, 410 suspected cases were reported in Catalonia: 348 fulfilled clinical case definition and 159 were laboratory confirmed. Incidence rate was 4.8 per 100,000 for cases that fulfilled the clinical definition, and 2.2 for laboratory confirmed cases. Global PPV was 44.5%; 38.5% in <15 years and 50% in > or =15 years (p=0.04). Most laboratory confirmed cases (72.3%) received at least one MMR dose. With sustained high MMR coverage, laboratory confirmation is necessary to control the disease and assess vaccine failure.